WO2016017507A1

WO2016017507A1 - Water content detection device, water content detection method, and water content detection program

Info

Publication number: WO2016017507A1
Application number: PCT/JP2015/070871
Authority: WO
Inventors: 友章房前
Original assignee: 株式会社いちごホールディングス; 房前日出子
Priority date: 2014-07-29
Filing date: 2015-07-22
Publication date: 2016-02-04
Also published as: US20170199142A1; CN106461808B; MY182898A; CN106461808A; JPWO2016017507A1; US10386317B2; JP6235146B2

Abstract

[Problem] To detect water content underground with a high degree of accuracy even without being a skilled technician. [Solution] A water content detection device 100 equipped with a current electrode pair 21, 22, a potential electrode pair 23, 24, a frequency setting unit 161, a specific resistance calculation unit 162, and an estimation unit 163. The frequency setting unit 161 sets the frequency for an AC current frequency at identical frequency intervals ΔF during a period from a first frequency F1 to a second frequency F2 (>F1). The specific resistance calculation unit 162 obtains a specific resistance value ρ for a prescribed region underground by using a current value A detected by the current electrode pair 21, 22, and a voltage value V detected by the potential electrode pair 23, 24, for each frequency setting. The estimation unit 163 obtains a maximum value ρ1 and a minimum value ρ2 for the specific resistance value ρ, and estimates the water content contained in the prescribed region to be increasing as the quotient obtained by dividing the maximum value ρ1 by the minimum value ρ2 decreases.

Description

Moisture detection device, moisture detection method, and moisture detection program

The present invention relates to a moisture detection device, a moisture detection method, and a moisture detection program for detecting moisture contained in a predetermined area in the ground.

Conventionally, a technique for detecting moisture contained in a predetermined area in the ground is known. For example, an apparatus for detecting groundwater veins by selecting four electrodes in a dipole / dipole arrangement with a changeover switch and switching the interval and position is disclosed (see Patent Document 1).

Patent Document 1 discloses a water vein detection device including a plurality of current electrode pairs, a plurality of potential electrode pairs, a first calculation means, a second calculation means, and an estimation means. The plurality of current electrode pairs measure a current value of an alternating current input to a predetermined region of the ground. The plurality of potential electrode pairs measure a voltage value corresponding to an alternating current. The first calculation means calculates a first specific resistance value indicating a specific resistance in a predetermined region of the ground using a current value and a voltage value based on an alternating current having a first frequency. The second calculation means uses a current value and a voltage value based on an alternating current having a second frequency that is higher than the first frequency, and a second specific resistance value indicating a specific resistance in a predetermined region of the ground. Is calculated. The estimation means estimates that the predetermined region of the ground includes a water vein when the second specific resistance value is greater than the first specific resistance value and the difference is equal to or greater than the predetermined value.

According to the water vein detection device, the water vein is detected based on two types of specific resistance values obtained by an alternating current having two types of frequencies in the same region in the ground, so that the water vein can be detected with high accuracy. Has been.

JP 2011-112357 A

However, in the water vein detection device described in Patent Document 1, it may be difficult to appropriately set the first frequency and the second frequency. In other words, the setting of the first frequency and the second frequency has been set based on the experience of a skilled engineer.

The moisture detection device, the moisture detection method, and the moisture detection program according to the present invention are made in view of the above problems, and detect moisture in the ground with high accuracy even if not a skilled engineer. It is an object.

The moisture detection device according to the present invention is a moisture detection device that detects moisture contained in a predetermined region in the ground. The moisture detection device includes a plurality of current electrode pairs, a plurality of potential electrode pairs, a frequency setting unit, a specific resistance calculation unit, and an estimation unit. The plurality of current electrode pairs measure a current value of an alternating current input to the predetermined region. The plurality of potential electrode pairs measure voltage values corresponding to the alternating current. The frequency setting means sets the frequency of the alternating current at a predetermined frequency interval between a preset first frequency and a second frequency higher than the first frequency. The specific resistance calculation means obtains a specific resistance value of the predetermined region using the current value and the voltage value every time the frequency is set by the frequency setting means. Further, the estimation means obtains the maximum value and the minimum value of the specific resistance value, and estimates that the smaller the quotient obtained by dividing the maximum value by the minimum value, the more water is contained in the predetermined region. .

The moisture detection device according to the present invention is a moisture detection device that detects moisture contained in a predetermined region in the ground. The moisture detection device includes a plurality of current electrode pairs, a plurality of potential electrode pairs, a frequency setting unit, a specific resistance calculation unit, a deviation calculation unit, and a frequency band selection unit. The plurality of current electrode pairs measure a current value of an alternating current input to the predetermined region. The plurality of potential electrode pairs measure voltage values corresponding to the alternating current. The frequency setting means sets the frequency of the alternating current at a predetermined frequency interval between a preset third frequency and a fourth frequency higher than the third frequency. The specific resistance calculation means obtains a specific resistance value of the predetermined region using the current value and the voltage value every time the frequency is set by the frequency setting means. The deviation calculating means divides the interval from the third frequency to the fourth frequency into two or more sections, and obtains a standard deviation of the specific resistance value obtained by the specific resistance calculating means for each of the sections. . The frequency band selecting means selects a frequency band corresponding to a section having the largest standard deviation obtained by the deviation calculating means as a frequency band used for detecting moisture contained in the ground.

The moisture detection method according to the present invention includes a plurality of current electrode pairs for measuring a current value of an alternating current input to a predetermined region in the ground, and a plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current. A moisture detection method using a moisture detection device that detects moisture contained in the predetermined area. The moisture detection method includes a frequency setting step, a specific resistance calculation step, and an estimation step. In the frequency setting step, the frequency of the alternating current is set at a predetermined frequency interval between a preset first frequency and a second frequency higher than the first frequency. In the specific resistance calculation step, every time a frequency is set in the frequency setting step, a specific resistance value indicating a specific resistance in the predetermined region is obtained using the current value and the voltage value. In the estimation step, the maximum value and the minimum value of the specific resistance value are obtained, and it is estimated that the smaller the quotient obtained by dividing the maximum value by the minimum value, the more moisture is contained in the ground of the predetermined region. To do.

The moisture detection method according to the present invention includes a plurality of current electrode pairs for measuring a current value of an alternating current input to a predetermined region in the ground, and a plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current. A moisture detection method using a moisture detection device that detects moisture contained in the predetermined area. The moisture detection method includes a frequency setting step, a specific resistance calculation step, a deviation calculation step, and a frequency band selection step. In the frequency setting step, a plurality of frequencies are set at predetermined frequency intervals between a preset third frequency and a fourth frequency higher than the third frequency. In the specific resistance calculation step, the specific resistance value in the predetermined region is obtained using the current value and the voltage value every time the frequency is set in the frequency setting step. In the deviation calculating step, the interval from the third frequency to the fourth frequency is divided into two or more sections, and a standard deviation of the specific resistance value obtained in the specific resistance calculating step is obtained for each section. . In the frequency band selecting step, a frequency band corresponding to a section having the largest standard deviation obtained in the deviation calculating step is selected as a frequency band used for detecting moisture contained in the ground.

The water detection program according to the present invention includes a plurality of current electrode pairs for measuring a current value of an alternating current input to a predetermined region in the ground, a plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current, A moisture detection program of a moisture detection device that includes a computer and detects moisture contained in the predetermined area. The moisture detection program causes the computer to function as frequency setting means, specific resistance calculation means, and estimation means. The frequency setting means sets the frequency of the alternating current at a predetermined frequency interval between a preset first frequency and a second frequency higher than the first frequency. The specific resistance calculation means obtains a specific resistance value indicating a specific resistance in the predetermined region by using the current value and the voltage value every time a frequency is set by the frequency setting means. The estimation means obtains the maximum value and the minimum value of the specific resistance value, and estimates that the smaller the quotient obtained by dividing the maximum value by the minimum value is, the more moisture is contained in the ground of the predetermined region. To do.

The water detection program according to the present invention includes a plurality of current electrode pairs for measuring a current value of an alternating current input to a predetermined region in the ground, a plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current, A moisture detection program of a moisture detection device that includes a computer and detects moisture contained in the predetermined area. The moisture detection program causes the computer to function as frequency setting means, specific resistance calculation means, deviation calculation means, and frequency band selection means. The frequency setting means sets the frequency of the alternating current at a predetermined frequency interval between a preset third frequency and a fourth frequency higher than the third frequency. The specific resistance calculation means obtains a specific resistance value of the predetermined region using the current value and the voltage value every time the frequency is set by the frequency setting means. The deviation calculating means divides the interval from the third frequency to the fourth frequency into two or more sections, and obtains a standard deviation of the specific resistance value obtained by the specific resistance calculating means for each of the sections. . The frequency band selecting means selects a frequency band corresponding to a section having the largest standard deviation obtained by the deviation calculating means as a frequency band used for detecting moisture contained in the ground.

According to the moisture detection apparatus, the moisture detection method, and the moisture detection program according to the present invention, it is possible to detect that the moisture in the ground is high with high accuracy even without being an expert engineer.

It is a figure which shows the measurement principle of the moisture detection apparatus which concerns on embodiment of this invention. (A) is a figure which shows the principle of a dipole dipole method, (b) is a figure which shows a measurable area | region. It is a block diagram which shows the structure of the moisture detection apparatus which concerns on embodiment of this invention. (A) is a block diagram which shows the whole structure of a moisture detection apparatus, (b) is a functional block diagram of the computer shown to (a). It is a flowchart which shows the process of the frequency selection process by the moisture detection apparatus shown in FIG. It is a flowchart which shows the process of the moisture detection process by the moisture detection apparatus shown in FIG. It is a figure which shows the experimental method for verifying the effect of the moisture detection apparatus shown in FIG. (A) is a perspective view which shows the shape and size of a water tank, (b) is sectional drawing which shows the state with which the water tank shown to (a) was buried in the ground, and the measuring point of a moisture detection apparatus. . It is a graph which shows the experimental result at the time of putting water into the water tank shown in FIG. It is a graph which shows the experimental result at the time of putting volcanic ash sandy soil and water in the water tank shown in FIG. (A) is a graph showing the relationship between frequency and specific resistance when the water content ratio is 60%, and (b) is a graph showing the relationship between frequency and specific resistance when the water content ratio is 70%. Yes, (c) is a graph showing the relationship between the frequency and the specific resistance when the water content ratio is 80%. It is a figure which shows distribution of the standard deviation for every frequency band at the time of putting water in the water tank shown in FIG. (A) shows the distribution of the standard deviation of the frequency band from 1 Hz to 20 Hz, (b) shows the distribution of the standard deviation of the frequency band from 21 Hz to 40 Hz, and (c) shows the distribution of the frequency band from 41 Hz to 60 Hz. The distribution of standard deviation is shown, (d) shows the distribution of standard deviation in the frequency band from 61 Hz to 80 Hz, and (e) shows the distribution of standard deviation in the frequency band of 81 Hz to 100 Hz. (F) is the standard deviation range. It is a graph which shows the main side line and the boring result in the place which verified the effect of the moisture detection apparatus shown in FIG. It is a graph which shows the position of the electrode arrange | positioned along the main side line shown in FIG. It is a figure which shows the detection result (distribution of a standard deviation) of the moisture detection apparatus along the main side line shown in FIG.

Hereinafter, a moisture detection apparatus according to an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

<Detection principle of resistivity ρ in the ground>
First, a moisture detection apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1A is a diagram showing the principle of the dipole-dipole method used in the moisture detection device 100 according to the embodiment of the present invention, and FIG. 1B is an overall configuration of the moisture detection device 100, and It is a figure which shows a measurable area | region and measurement point MP.

As shown in FIG. 1A, the moisture detection device 100 includes current electrode pairs 21 and 22 and potential electrode pairs 23 and 24. The current electrode pairs 21 and 22 are partially embedded in the ground SF at a distance L. Similarly, the potential electrode pairs 23 and 24 are partially buried in the ground SF at a distance L. Here, the distance between the current electrode 22 and the potential electrode 23 is set to an integral multiple of the distance L (here, n times). In this case, the specific resistance value ρ at the point Q at a depth (L × (n + 1) / 2) from the ground at the midpoint P between the current electrode 22 and the potential electrode 23 is expressed by the following equation (1). As shown in FIG.
ρ = n × (n + 1) × (n + 2) × π × L × (V / A) (1)
Here, the voltage value V is a voltage value detected by the potential electrode pair 23, 24, and the current value A is a current value detected by the

current electrode pair

21, 22.

As shown in FIG. 1B, the moisture detection device 100 includes a moisture detection device main body 1, an electrode 2, and a lead wire 3. The electrode 2 is partially buried in the ground SF at a distance L, and functions as the

current electrode pair

21, 22 or the potential electrode pair 23, 24. Here, a plurality of electrodes 2 (31 in this case) are provided. The lead wire 3 connects the electrode 2 and the moisture detection device main body 1 so that energization is possible. Specifically, the lead wire 3 connects the electrode 2 and an electrode switching circuit 14 to be described later with reference to FIG. The moisture detection device main body 1 sets two of the 31 electrodes 2 as current electrode pairs 21 and 22 and the other two as potential electrode pairs 23 and 24 via the lead wire 3. Further, as shown in FIG. 1B, a broken trapezoidal region R shown below the ground SF is a detectable region indicating a range that can be detected by the moisture detection device 100. Note that one base (upper base) of the trapezoidal region R is located on the ground SF and is a line segment connecting the midpoint of the two leftmost electrodes and the midpoint of the two rightmost electrodes. .

<Hardware configuration of moisture detection device main body 1>
Next, the configuration of the moisture detection device main body 1 will be described with reference to FIG. FIG. 2A is a block diagram showing the overall configuration of the moisture detection device main body 1, and FIG. 2B is a functional block diagram of the computer 16 shown in FIG. As shown in FIG. 2A, the moisture detection device main body 1 includes a DC stabilized power supply 11, an oscillator 12, a rectangular wave drive circuit 13, an electrode switching circuit 14, a data logger 15, and a computer 16.

DC stabilized power supply 11 generates and outputs a direct current (in this case, for example, 1.3 amperes) from an AC 100V commercial power supply. The oscillator 12 outputs an AC signal having a frequency of 1 Hz to 100 Hz based on an instruction from the computer 16. The rectangular wave drive circuit 13 outputs a rectangular wave current of FαHz by using a direct current input from the direct current stabilized power supply 11 and an alternating current signal (here, FαHz for convenience) input from the oscillator 12. To do. The electrode switching circuit 14 sets two of the 31 electrodes 2 shown in FIG. 1B as current electrode pairs 21 and 22 and sets the other two as potential electrode pairs 23 and 24. Further, the electrode switching circuit 14 applies the FαHz rectangular wave current (current value A) input from the rectangular wave drive circuit 13 to the set

current electrode pair

21 and 22. Further, the electrode switching circuit 14 detects the voltage value V from the set potential-voltage pair 23, 24.

The data logger 15 includes identification information for identifying the

current electrode pair

21 and 22, current value A of the rectangular wave current applied to the

current electrode pair

21 and 22, identification information for identifying the potential electrode pair 23 and 24, and the potential The voltage value V detected from the electrode pair 23, 24 is stored. Here, the

current electrode pair

21 and 22 and the potential electrode pair 23 and 24 are set by the electrode switching circuit 14. Further, the data logger 15 stores the above four pieces of information every predetermined time (for example, 10 msec).

The computer 16 acquires the frequency F of the rectangular wave current applied from the oscillator 12 to the current electrode pairs 21 and 22. The computer 16 also identifies identification information for identifying the

current electrode pair

21, 22 from the data logger 15, identification information for identifying the potential electrode pair 23, 24, and the current value of the rectangular wave current applied to the

current electrode pair

21, 22. A and the voltage value V detected from the potential electrode pair 23, 24 are acquired. Further, the computer 16 instructs the oscillation frequency to the oscillator 12. In addition, the computer 16 has a functional unit shown in FIG.

<Functional configuration of moisture detection device main body 1>
The computer 16 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disk Drive). The ROM (or the HDD) stores a control program including a moisture detection program according to the present invention. The CPU reads and executes the moisture detection program stored in the ROM (or the HDD), thereby executing a frequency setting unit 161, a specific resistance calculation unit 162, an estimation unit 163, a deviation calculation unit 164, and And function as various functional units including the frequency band selecting unit 165. The RAM is used as a work area when the CPU executes the moisture detection program.

When the “moisture detection process” shown in FIG. 4 is performed, the frequency setting unit 161 sets the frequency Fα of the alternating current (here, rectangular wave current) applied to the current electrode pairs 21 and 22 to a preset first frequency Fα. Between the first frequency F1 and the second frequency F2 higher than the first frequency F1, a plurality of frequencies are set at the same frequency interval ΔF. Here, the frequency setting unit 161 corresponds to an example of “frequency setting means”. The frequency interval ΔF corresponds to an example of “predetermined frequency interval”. In the present embodiment, a case where the first frequency F1 is 21 Hz, the second frequency F2 is 40 Hz, and the frequency interval ΔF is 1 Hz will be described. That is, in the present embodiment, the frequency setting unit 161 sets a frequency for every 1 Hz in the range of 21 Hz to 40 Hz. In the present embodiment, the case where the frequency setting unit 161 sets a plurality of frequencies at the same frequency interval ΔF will be described. However, the frequency setting unit 161 may set a plurality of frequencies by other methods. .

Further, when performing the “frequency selection process” shown in FIG. 3, the frequency setting unit 161 has a third frequency F3 lower than the first frequency F1 to a fourth frequency F4 higher than the second frequency F2. A plurality of frequencies are set at the same frequency interval ΔF. In the present embodiment, a case where the third frequency F3 is 1 Hz, the fourth frequency F4 is 100 Hz, and the frequency interval ΔF is 1 Hz will be described. That is, in the present embodiment, the frequency setting unit 161 sets a frequency every 1 Hz in a range of 1 Hz to 100 Hz.

The specific resistance calculation unit 162 is detected from the current value A of the rectangular wave current applied to the

current electrode pair

21 and 22 and the potential electrode pair 23 and 24 each time the frequency Fα is set by the frequency setting unit 161. Using the voltage value V, a specific resistance value ρ indicating the specific resistance of a predetermined region in the ground is obtained. Here, the specific resistance calculation unit 162 corresponds to an example of “specific resistance calculation means”.

In this embodiment, since the rectangular wave current is applied to the current electrode pairs 21 and 22, the time for which the maximum current value flows is long. Moreover, since the S / N ratio can be increased as the current value increases, the detection accuracy of the specific resistance value ρ is high. Therefore, an accurate specific resistance value ρ can be obtained by applying a rectangular wave current to the

current electrode pair

21, 22.

In the present embodiment, a case where a rectangular wave current is applied to the current electrode pairs 21 and 22 will be described, but any form in which an alternating current is applied to the current electrode pairs 21 and 22 may be used. For example, a form in which a sinusoidal alternating current is applied to the

current electrode pair

21, 22 or a form in which a triangular wave alternating current is applied to the

current electrode pair

21, 22 may be used.

The estimation unit 163 obtains the maximum value ρ1 and the minimum value ρ2 of the specific resistance value ρ, and the smaller the quotient (ρ1 / ρ2) obtained by dividing the maximum value ρ1 by the minimum value ρ2, the moisture contained in the predetermined region It is estimated that there are many. Here, the estimation unit 163 corresponds to an example of “estimating means”.

As will be described later with reference to FIG. 6, when there is water in the predetermined region (the water content is 100%), the specific resistance value of the predetermined region can be obtained even if the frequency Fα is changed between 1 Hz and 100 Hz. ρ hardly changes. As will be described later with reference to FIG. 7, the more the moisture contained in the predetermined region, the more the frequency Fα is changed between 1 Hz and 100 Hz (particularly, the frequency Fα is changed between 21 Hz and 40 Hz). Change in the specific resistance value ρ (in this case, the variation corresponding to the deviation) is reduced. Therefore, when the frequency Fα is changed between 21 and 40 Hz, the smaller the quotient (ρ1 / ρ2) obtained by dividing the maximum value ρ1 of the specific resistance value ρ by the minimum value ρ2, the more included in the predetermined region. It can be estimated that there is much moisture.

In the present embodiment, the frequency setting unit 161 sets the frequency Fα of the alternating current applied to the current electrode pairs 21 and 22 for each 1 Hz in the range of 21 Hz to 40 Hz, so 20 frequencies are set. Twenty specific resistance values ρ corresponding to the set 20 frequencies are obtained. Therefore, the estimation unit 163 can appropriately obtain the maximum value ρ1 and the minimum value ρ2.

In other words, the frequency interval ΔF is preferably 1 Hz or less, and the frequency setting unit 161 preferably sets 10 or more frequencies. This is because the estimation unit 163 estimates that the smaller the quotient (ρ1 / ρ2) obtained by dividing the maximum value ρ1 by the minimum value ρ2 is, the more moisture is contained in the predetermined region. It is necessary to determine the value ρ2. Accordingly, it is preferable that the frequency setting unit 161 sets a large number (at least 10 or more) frequencies by reducing the frequency interval ΔF.

The deviation calculation unit 164 divides the interval from the third frequency F3 to the fourth frequency F4 into two or more sections ARk, and the standard deviation of the specific resistance value ρ obtained by the specific resistance calculation unit 162 for each section ARk. Find σ. Here, the deviation calculating unit 164 corresponds to an example of “deviation calculating means”. In the present embodiment, as will be described later with reference to FIG. 7A, there are five sections ARk (here, k = b) from 1 Hz that is the third frequency F3 to 100 Hz that is the fourth frequency F4. A case of dividing equally into 1 to 5) will be described. Here, the standard deviation σ corresponding to the section ARk is expressed as standard deviation σk (k = 1 to 5).

The frequency band selecting unit 165 selects the frequency band FRh corresponding to the section ARh having the largest standard deviation σ obtained by the deviation calculating unit 164 as the frequency band FRh used for detecting moisture contained in the ground. To do. Here, the frequency band selection unit 165 corresponds to an example of “frequency band selection means”. In the present embodiment, as will be described later with reference to FIG. 7A, the frequency band FR2 (21 Hz to 40 Hz) corresponding to the section AR2 having the largest standard deviation σ is contained in the moisture contained in the ground. The frequency band FR2 used for detection is selected.

In other words, the first frequency F1 set by the frequency setting unit 161 is the lower limit frequency (21 Hz) of the frequency band FRh (frequency band FR2 in the example shown in FIG. 7) selected by the frequency band selection unit 165. The second frequency F2 is the upper limit frequency (40 Hz) of the frequency band FRh (in the example shown in FIG. 7, the frequency band FR2) selected by the frequency band selection unit 165.

By setting the first frequency F1 and the second frequency F2 as described above, it is possible to appropriately set the frequency range when performing the moisture detection process shown in FIG. Therefore, it is possible to accurately determine whether or not there is much moisture in the moisture detection process.

<Operation of Moisture Detection Device Main Body 1>
Next, the frequency selection process will be described with reference to FIG. Here, the frequency selection process is a process of selecting a frequency band FRh used for detecting moisture contained in the ground. FIG. 3 is a flowchart showing a frequency selection process performed by the moisture detection apparatus 100 shown in FIG. First, the deviation calculation unit 164 performs two or more (here, five) sections ARk (here, five) from the third frequency F3 (here, 1 Hz) to the fourth frequency F4 (here, 100 Hz). k = 1 to 5) (step S101). Next, the frequency setting unit 161 sets the frequency at a frequency interval ΔF (here, 1 Hz) for each section ARk (here, k = 1 to 5) (step S103). Here, step S103 corresponds to an example of a “frequency setting step”.

Then, every time the frequency is set in step S103, the specific resistance calculation unit 162 calculates the specific resistance value ρ (step S105). Here, step S105 corresponds to an example of a “specific resistance calculation step”. Next, the standard deviation σ of the specific resistance value ρ obtained in step S105 is obtained by the deviation calculating unit 164 for each section ARk (step S107). Here, step S107 corresponds to an example of a “deviation calculation step”. Then, it is determined whether or not the measurement of all sections ARk is completed (step S109).

If it is determined that the measurement of all sections ARk has not been completed (NO in step S109), the process returns to step S103, and the processes after step S103 are executed. When it is determined that measurement of all sections ARk is completed (YES in step S109), the frequency band FRh corresponding to the section ARh having the largest standard deviation σ obtained in step S107 by the frequency band selecting unit 165 is determined. The frequency band FRh used for detecting moisture contained in the ground is selected (step S111), and the process is terminated. Here, step S111 corresponds to an example of a “frequency selection step”.

In this way, in order to select the frequency band FRh corresponding to the section ARh having the largest standard deviation σ as the frequency band FRh used for detecting moisture contained in the ground, the appropriate frequency band FRh is selected. can do. In other words, in the frequency band FRh corresponding to the section ARh having the largest standard deviation σ, the change in the specific resistance value ρ when the frequency changes is large. Therefore, when there is not a lot of moisture contained in the ground, the quotient (ρ1 / ρ2) obtained by dividing the maximum value ρ1 of the specific resistance value ρ obtained by the estimation unit 163 by the minimum value ρ2 becomes large. The estimation by 163 becomes easy.

In the present embodiment, the frequency band selecting unit 165 selects the frequency band FRh corresponding to the section ARh having the largest standard deviation σ as the frequency band FRh used for detecting moisture contained in the ground. As will be described, the frequency band FRh may be selected by other methods. For example, the frequency band selection unit 165 may select a frequency band FRk having a large variation in specific resistance value ρ. Specifically, the maximum value and the minimum value of the specific resistance value ρ for each frequency band FRk may be obtained, and the frequency band FRk that maximizes the difference between the two may be selected. Alternatively, the maximum value and the minimum value of the specific resistance value ρ for each frequency band FRk may be obtained, and the frequency band FRk having the maximum quotient obtained by dividing the maximum value by the minimum value may be selected.

Next, the process of moisture detection processing will be described with reference to FIG. Here, the moisture detection process is a process for detecting whether or not there is a lot of moisture contained in a predetermined area in the ground. FIG. 4 is a flowchart showing a process of moisture detection processing by the moisture detection apparatus 100 shown in FIG. First, the frequency setting unit 161 sets the frequency at the same frequency interval ΔF (here 1 Hz) from the first frequency F1 (here 21 Hz) to the second frequency F2 (here 40 Hz). (Step S201). Here, step S201 corresponds to an example of a “frequency setting step”.

Then, every time the frequency is set in step S201, the specific resistance calculation unit 162 measures the specific resistance value ρ (step S203). Here, step S203 corresponds to an example of a “specific resistance calculation step”. Next, it is determined whether or not the measurement of the specific resistance value ρ has been completed for all frequencies (step S205). If it is determined that the measurement of the specific resistance value ρ has not been completed for all frequencies (NO in step S205), the process returns to step S201, and the processes after step S201 are executed. When it is determined that the measurement of the specific resistance value ρ has been completed for all frequencies (YES in step S205), the estimation unit 163 obtains the maximum value ρ1 and the minimum value ρ2 of the specific resistance value ρ (step S205). S207).

Next, the estimation unit 163 determines whether or not a quotient (ρ1 / ρ2) obtained by dividing the maximum value ρ1 by the minimum value ρ2 is equal to or less than a preset threshold value S (step S209). When it is determined that the quotient (ρ1 / ρ2) is equal to or less than the threshold value S (YES in step S209), the estimation unit 163 estimates that the moisture contained in the predetermined area is large (step S211). Processing is terminated. When it is determined that the quotient (ρ1 / ρ2) is greater than the threshold value S (NO in step S209), the estimation unit 163 estimates that the moisture contained in the predetermined area is small (step S213). The process is terminated. Here, step S207 to step S213 correspond to an example of an “estimation process”.

In this way, when it is determined that the quotient (ρ1 / ρ2) is equal to or less than the threshold value S, the estimation unit 163 estimates that a large amount of water is contained in a predetermined region in the ground, so Even if it is not an engineer, it can detect that there is much moisture in the ground with high accuracy.

In the present embodiment, the estimation unit 163 has described the case where it is estimated that the smaller the quotient (ρ1 / ρ2) obtained by dividing the maximum value ρ1 by the minimum value ρ2, the more moisture is contained in the predetermined region. Any configuration may be used as long as the estimation unit 163 estimates that the moisture content included in the predetermined region is larger as the variation in the specific resistance value ρ is smaller. For example, the estimation unit 163 may estimate that the smaller the standard deviation σ of the specific resistance value ρ is, the more moisture is contained in the predetermined region. Further, for example, the smaller the value ((ρ1−ρ2) / ρA) obtained by dividing the difference obtained by subtracting the minimum value ρ2 from the maximum value ρ1 by the average value ρA of the specific resistance value ρ, the moisture contained in the predetermined region It may be a form that is estimated to be large.

<Experiment to verify the effect>
Next, an experimental method for verifying the effect of the moisture detection apparatus 100 according to the present invention and experimental results will be described with reference to FIGS. FIG. 5 is a diagram showing an experimental method for verifying the effect of the moisture detection apparatus shown in FIG. FIG. 5A is a perspective view showing the shape and size of the water tank 4, and FIG. 5B shows the state in which the water tank 4 shown in FIG. It is sectional drawing which shows a measurement point.

As shown in FIG. 5 (a), the water tank 4 has an internal size and is formed in a rectangular parallelepiped shape having a width of 30 cm, a length of 22 cm, and a height of 18 cm. The water tank 4 is filled with water or a mixture of water and volcanic ash sandy soil.

As shown in FIG. 5B, the water tank 4 has water (or a mixture of water and volcanic ash sandy soil) in the water tank 4 within a range of 7 cm to 25 cm in depth from the ground SF. Buried in position. In addition, the water tank 4 is buried at the center position of the 150 cm wide region where the electrode 2 of the moisture detecting device 100 is buried. The water tank 4 is embedded directly below the electrode 2 so that the width direction of the water tank 4 is positioned along the direction in which the electrode 2 is embedded. That is, the water tank 4 is embedded so that the vertical plane including the electrode 2 passes through the center position in the length direction of the water tank 4. In addition, the measurement point MP in FIG. 5B is a point where the specific resistance value ρ is detected by the moisture detection device 100.

FIG. 6 is a graph G1 showing experimental results when water is put into the water tank 4 shown in FIG. The horizontal axis indicates the frequency F (Hz) of the current to be applied, and the vertical axis indicates the specific resistance value ρ (Ω · m) at the measurement point MP closest to the center position of the water put in the water tank 4. As shown in the graph G1, the specific resistance value ρ hardly changes even when the frequency F is changed from 1 Hz to 100 Hz.

FIG. 7 is a graph showing experimental results when a mixture of volcanic ash sandy soil and water is put in the water tank 4 shown in FIG. FIG. 7A shows the case where the water content of the mixture is 60% (40% volcanic ash sandy soil and 60% water), and FIG. 7B shows that the water content of the mixture is 70% (volcanic ash Fig. 7 (c) shows the case where the water content of the mixture is 80% (20% volcanic ash sandy soil and 80% water). is there. As in FIG. 6, in FIGS. 7A, 7 </ b> B, and 7 </ b> C, the horizontal axis represents the frequency F (Hz) of the applied current, and the vertical axis represents the mixture placed in the water tank 4. The specific resistance value ρ (Ω · m) at the measurement point MP closest to the center position is shown.

When comparing the graph G1 shown in FIG. 6, the graph G2 shown in FIG. 7A, the graph G3 shown in FIG. 7B, and the graph G4 shown in FIG. It can be seen that the change (variation) in the vertical direction is small.

Further, for example, as shown in FIG. 7A, the frequency of 1 Hz to 100 Hz is divided into five sections AR1 to AR5. Then, the standard deviation σk (k = 1 to 5) for each section ARk (k = 1 to 5) is obtained by the deviation calculator 164 shown in FIG. Here, standard deviation σ1 = 0.4431, standard deviation σ2 = 0.6479, standard deviation σ3 = 0.5990, standard deviation σ4 = 0.5966, standard deviation σ5 = 0.3470, and standard deviation σ2 of section AR2 Is the maximum. Accordingly, the frequency band selection unit 165 shown in FIG. 2B uses the frequency band FR2 (21 Hz to 40 Hz) corresponding to the section AR2 having the largest standard deviation σ to detect moisture contained in the ground. It is selected as the frequency band FR2 to be used.

Further, FIG. 7A shows a maximum value ρ11 of the specific resistance value ρ and a minimum value ρ21 of the specific resistance value ρ in the section AR2. Similarly, FIG. 7B shows a maximum value ρ12 and a minimum value ρ22 of the specific resistance value ρ in the section AR2, and FIG. 7C shows a specific resistance value ρ in the section AR2. The maximum value ρ13 and the minimum value ρ23 of the specific resistance value ρ are shown.

The quotient (ρ1 / ρ2) obtained by dividing the maximum value ρ1 of the specific resistance value ρ in the section AR2 by the minimum value ρ2 is 1.045 when the water content ratio shown in FIG. When the water content ratio shown in (b) is 70%, it becomes 1.012, and when the water content ratio shown in FIG. 7 (c) is 80%, it becomes 1.009. Therefore, it can be estimated that the smaller the quotient (ρ1 / ρ2) obtained by dividing the maximum value ρ1 of the resistivity ρ by the minimum value ρ2, the more moisture in the ground.

FIG. 8 is a diagram showing a standard deviation distribution for each frequency band when gravel and water are put into the water tank 4 shown in FIG. 8A shows a case where the frequency band is 1 Hz to 20 Hz, FIG. 8B shows a case where the frequency band is 21 Hz to 40 Hz, and FIG. 8C shows that the frequency band is 41 Hz to 60 Hz. FIG. 8D shows a case where the frequency band is 61 Hz to 80 Hz, and FIG. 8E shows a case where the frequency band is 81 Hz to 100 Hz. FIG. 8F shows the range of the standard deviation σ.

8 (a) to 8 (e), the horizontal axis indicates the distance (cm) in the width direction from the measurement point MP at the left end by the moisture detection device 100, and the vertical axis indicates by the moisture detection device 100. The depth (cm) of the measurement point MP is shown. 8 (a) to 8 (e), as standard deviation distributions, contour lines (lines connecting measurement points MP having the same standard deviation σ) and shaded areas indicating the size of the standard deviation σ are shown. Is described. Here, the darker the shading, the larger the standard deviation σ.

8A to 8E, each rectangle W represents the position of water in the water tank 4 shown in FIG. 8 (a) to 8 (e) are compared, and FIG. 8 (b) shows that the standard deviation σ in the region inside the rectangle W is particularly large and the frequency band is 21 Hz to 40 Hz. It turns out that the position of water is easy to detect. In addition, this result has shown that the frequency band selection part 165 shown in FIG.2 (b) has selected appropriately the frequency band FR2 used in order to detect the water | moisture content contained in the ground. In other words, the frequency band selecting unit 165 appropriately detects the moisture contained in the ground by selecting the frequency band FR2 (21 Hz to 40 Hz) corresponding to the section AR2 having the largest standard deviation σ. It shows that you can.

<Results of verification of effect of moisture detector>
Next, the results of verifying the effect of the moisture detection apparatus 100 shown in FIG. 1 will be described with reference to FIGS. FIG. 9 is a graph showing the main side line G5 and the borehole investigation result at the place where the effect of the moisture detection apparatus 100 is verified. The horizontal axis indicates the distance L, and the vertical axis indicates the altitude H. Boring was performed at three positions P1 to P3 along the main side line G5.

In the boring survey, the maximum strain amount and strain depth ST1 to ST3 and the water levels WL1 to WL3 were investigated. Specifically, at position P1, drilling was performed at a depth of 30 m. In FIG. 9, the distortion depths ST1 to ST3 at the boring positions P1 to P3 are indicated by circles (◯), and the depth of the water level is indicated by triangles (Δ). The distortion depth ST1 at the boring position P1 was 6 m, the maximum distortion amount was 200 μST, and the depth of the water level was 24.4 m. At the position P2, boring with a depth of 17 m was performed. The distortion depth ST2 at the boring position P2 was 6 m, the maximum distortion amount was 600 μST, and the depth of the water level was 16.9 m. At position P3, drilling was performed at a depth of 15 m. Further, the strain depth ST3 at the boring position P3 was 8 m, the maximum strain amount was 150 μST, and the depth of the water level was 5.5 m.

It is known that landslides occur at the positions of the distortion depths ST1 to ST3. On the other hand, as described with reference to FIG. 9, the positions of the distortion depths ST1 to ST3 and the water levels WL1 to WL3 are greatly different. That is, it is necessary to investigate whether or not there is a water layer other than the positions of the water levels WL1 to WL3 obtained by the boring survey. Therefore, the inventors investigated the position where water exists using the moisture detection device 100.

Next, the arrangement of the electrodes 2a will be described with reference to FIG. FIG. 10 is a graph showing the positions of the electrodes arranged along the main side line G5. The horizontal axis indicates the distance L, and the vertical axis indicates the altitude H. 51 electrodes 2a were arranged along the main side line G5 at intervals of 3 m.

Next, the detection result of the moisture detection apparatus 100 will be described with reference to FIG. FIG. 11 is a diagram showing the detection result (distribution of standard deviation σ) of the moisture detection device 100 along the main side line G5. The horizontal axis indicates the distance L, and the vertical axis indicates the altitude H. Here, the darker the shading, the larger the standard deviation σ. As shown in FIG. 11, it was found that a water layer exists in the range of 5 to 10 m from the ground surface along the main side line G5. This result was in good agreement with the distortion depths ST1 to ST3. In other words, as a result of the verification shown in FIGS. 9 to 11, it was found that the moisture detection device 100 can properly detect the moisture contained in the ground.

In the present embodiment, the case where the frequency setting unit 161 sets the frequency with the frequency interval ΔF set to 1 Hz has been described, but the frequency setting unit 161 preferably sets the frequency interval ΔF to 1 Hz or less. As the frequency interval ΔF is smaller, the deviation calculating unit 164 can obtain an appropriate standard deviation σ, and thus the frequency band selecting unit 165 can select an appropriate frequency band. However, the processing time of the specific resistance calculation unit 162, the deviation calculation unit 164, and the frequency band selection unit 165 becomes longer as the frequency interval ΔF is smaller.

Similarly, as the frequency interval ΔF is smaller, the estimation unit 163 can obtain appropriate values as the maximum value ρ1 and the minimum value ρ2 of the specific resistance value ρ. Therefore, the estimation unit 163 appropriately determines whether or not there is much moisture. Can be estimated.

In the present embodiment, the case where the frequency setting unit 161 sets the frequency in the range of 1 Hz to 100 Hz has been described, but the range in which the frequency setting unit 161 sets the frequency is not limited to the above range. For example, the frequency may be 1 Hz to 50 Hz, or 1 Hz to 200 Hz. As the frequency setting unit 161 sets the frequency over a wide range, the frequency band selection unit 165 easily obtains an appropriate frequency band.

In the present embodiment, the case where the deviation calculation unit 164 divides the range from the third frequency F3 to the fourth frequency F4 into five sections ARk has been described. However, the deviation calculation unit 164 divides the section into a plurality of sections. I just need it. As the number of divisions is increased, an appropriate frequency band is easily obtained. However, the processing time of the deviation calculation unit 164 and the frequency band selection unit 165 becomes longer as the number of divisions is larger. If the number of divisions is too large, the number of frequencies included in one division among the frequencies set by the frequency setting unit 161 decreases, and the standard deviation σ cannot be obtained appropriately. It is necessary to determine the number of sections to be divided so that the number of frequencies included in one section is, for example, 10 or more.

The embodiment of the present invention has been described above with reference to the drawings (FIGS. 1 to 11). However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof.

In addition, in order to make it easy to understand, the drawings schematically show each component mainly. Accordingly, the thickness, length, and the like of each illustrated component may differ from the actual one for the convenience of drawing.

The present invention can be applied to a moisture detection device, a moisture detection method, and a moisture detection program for detecting moisture in the ground.

DESCRIPTION OF SYMBOLS 100 Moisture detection apparatus 1 Moisture detection apparatus main body 11 DC stabilized power supply 12 Oscillator 13 Rectangular wave drive circuit 14 Electrode switching circuit 15 Data logger 16 Computer 161 Frequency setting part (frequency setting means)
162 Specific resistance calculation unit (specific resistance calculation means)
163 Estimating unit (estimating means)
164 Deviation calculation unit (deviation calculation means)
165 Frequency band selection section (frequency band selection means)
2

Electrodes

21 and 22 Current electrode pair 23 and 24 Potential electrode pair 3 Lead wire 4 Water tank

Claims

A moisture detection device for detecting moisture contained in a predetermined area in the ground,
A plurality of current electrode pairs for measuring the current value of the alternating current input to the predetermined region;
A plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current;
A frequency setting means for setting a plurality of frequencies at predetermined frequency intervals between a first frequency set in advance and a second frequency higher than the first frequency, the frequency of the alternating current;
Resistivity calculating means for obtaining a specific resistance value in the predetermined region using the current value and the voltage value each time a frequency is set by the frequency setting means;
An estimation means for obtaining a maximum value and a minimum value of the specific resistance value, and estimating that the smaller the quotient obtained by dividing the maximum value by the minimum value is, the more moisture is contained in the predetermined area; Detection device.
The moisture detection apparatus according to claim 1, wherein the frequency interval is 1 Hz or less, and the frequency setting means sets 10 or more frequencies.
The frequency setting means sets a plurality of frequencies at the predetermined frequency interval between a third frequency lower than the first frequency and a fourth frequency higher than the second frequency,
Deviation calculation means for dividing the interval from the third frequency to the fourth frequency into two or more sections, and obtaining a standard deviation of the specific resistance value obtained by the specific resistance calculation means for each section;
The frequency band selecting means for selecting a frequency band corresponding to a section having the largest standard deviation obtained by the deviation calculating means as a frequency band used for detecting moisture contained in the ground. The moisture detection apparatus according to claim 1 or 2.
The first frequency is a lower limit frequency of the frequency band selected by the frequency band selecting means,
The moisture detection apparatus according to claim 3, wherein the second frequency is an upper limit frequency of a frequency band selected by the frequency band selecting unit.
The moisture detection device according to any one of claims 1 to 4, wherein the first frequency is approximately 20 Hz, and the second frequency is approximately 40 Hz.
The moisture detection device according to any one of claims 1 to 5, wherein the alternating current is a rectangular wave alternating current.
A moisture detection device for detecting moisture contained in a predetermined area in the ground,
A plurality of current electrode pairs for measuring the current value of the alternating current input to the predetermined region;
A plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current;
A frequency setting means for setting a plurality of frequencies at predetermined frequency intervals between a preset third frequency and a fourth frequency higher than the third frequency, the frequency of the alternating current;
Resistivity calculating means for obtaining a specific resistance value in the predetermined region using the current value and the voltage value each time a frequency is set by the frequency setting means;
Deviation calculation means for dividing the interval from the third frequency to the fourth frequency into two or more sections, and obtaining a standard deviation of the specific resistance value obtained by the specific resistance calculation means for each section;
A frequency band selecting means for selecting a frequency band corresponding to a section having the largest standard deviation obtained by the deviation calculating means as a frequency band used for detecting moisture contained in the ground, apparatus.
A plurality of current electrode pairs for measuring a current value of an alternating current input to a predetermined region in the ground, and a plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current, and included in the predetermined region A moisture detection method using a moisture detection device that detects moisture,
A frequency setting step of setting a plurality of frequencies at a predetermined frequency interval between a first frequency set in advance and a second frequency higher than the first frequency, the frequency of the alternating current;
A specific resistance calculation step for obtaining a specific resistance value indicating a specific resistance of the predetermined region using the current value and the voltage value each time a frequency is set in the frequency setting step;
An estimation step of obtaining a maximum value and a minimum value of the specific resistance value, and estimating that the smaller the quotient obtained by dividing the maximum value by the minimum value is, the more moisture is contained in the ground of the predetermined region. A moisture detection method.
In the frequency setting step, between a third frequency lower than the first frequency and a fourth frequency higher than the second frequency, a plurality of frequencies are set at the predetermined frequency interval,
A deviation calculating step of dividing the interval from the third frequency to the fourth frequency into two or more sections, and obtaining a standard deviation of the specific resistance value obtained in the specific resistance calculating step for each of the sections;
A frequency band selecting step of selecting a frequency band corresponding to a section having the largest standard deviation obtained in the deviation calculating step as a frequency band used for detecting moisture contained in the ground. The moisture detection method according to 8.
A plurality of current electrode pairs for measuring a current value of an alternating current input to a predetermined region in the ground, and a plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current, and included in the predetermined region A moisture detection method using a moisture detection device that detects moisture,
A frequency setting step of setting a plurality of frequencies at a predetermined frequency interval between a preset third frequency and a fourth frequency higher than the third frequency, the frequency of the alternating current;
A specific resistance calculation step for obtaining a specific resistance value in the predetermined region using the current value and the voltage value each time a frequency is set in the frequency setting step;
A deviation calculating step of dividing the interval from the third frequency to the fourth frequency into two or more sections, and obtaining a standard deviation of the specific resistance value obtained in the specific resistance calculating step for each of the sections;
A frequency band selecting step of selecting a frequency band corresponding to a section having the largest standard deviation obtained in the deviation calculating step as a frequency band used for detecting moisture contained in the ground. Method.
A plurality of current electrode pairs for measuring a current value of an alternating current input to a predetermined region in the ground, a plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current, and a computer; A moisture detection program for a moisture detection device for detecting contained moisture,
A frequency setting means for setting the frequency of the alternating current between a first frequency set in advance to a second frequency higher than the first frequency at a predetermined frequency interval;
Resistivity calculation means for obtaining a specific resistance value indicating a specific resistance of the predetermined region using the current value and the voltage value each time the frequency is set by the frequency setting means;
An estimation means for obtaining a maximum value and a minimum value of the specific resistance value, and estimating that the smaller the quotient obtained by dividing the maximum value by the minimum value, the more water is contained in the ground of the predetermined region. Moisture detection program.
The frequency setting means sets a plurality of frequencies at the predetermined frequency interval between a third frequency lower than the first frequency and a fourth frequency higher than the second frequency,
Said computer further
Deviation calculation means for dividing the interval from the third frequency to the fourth frequency into two or more sections, and obtaining a standard deviation of the specific resistance value obtained by the specific resistance calculation means for each section;
Function as a frequency band selecting means for selecting a frequency band corresponding to a section having the largest standard deviation obtained by the deviation calculating means as a frequency band used for detecting moisture contained in the ground, The moisture detection program according to claim 11.
A plurality of current electrode pairs for measuring a current value of an alternating current input to a predetermined region in the ground, a plurality of potential electrode pairs for measuring a voltage value corresponding to the alternating current, and a computer; A moisture detection program for a moisture detection device for detecting contained moisture,
A frequency setting means for setting the frequency of the alternating current between a preset third frequency and a fourth frequency higher than the third frequency at a predetermined frequency interval;
Resistivity calculating means for obtaining a specific resistance value in the predetermined region using the current value and the voltage value each time a frequency is set by the frequency setting means;
Deviation calculation means for dividing the interval from the third frequency to the fourth frequency into two or more sections, and obtaining a standard deviation of the specific resistance value obtained by the specific resistance calculation means for each section;
Function as a frequency band selecting means for selecting a frequency band corresponding to a section having the largest standard deviation obtained by the deviation calculating means as a frequency band used for detecting moisture contained in the ground, Moisture detection program.